"Enough!" said a post on the 9NEWS Facebook page. "I am, like nearly everyone I know, sick of hearing about marijuana, dope smokers, stoners, etc!!!!!!!"

Some medical professionals can't escape hearing about marijuana use, and instead say they're hearing about it much more frequently.
"We're seeing a lot more patients, a lot more youth coming to treatment for marijuana addiction," said Dr. Christian Thurstone, the medical director of the adolescent substance program at Denver Health, who is also part of a research team conducting a 5-year study on the impacts of marijuana legalization.

Thurstone says those addiction numbers have grown since medical marijuana went on sale in Colorado, to the point that the program has had to double its number of therapists to keep up with demand.

"If somebody tries marijuana before the age of 18, one in six develops an addiction to the drug," Thurstone said. "If someone waits until after 18, the number is more like one in nine."

He says there's a growing perception that marijuana is safe, especially because it's legal now. But he points to risks he says are most serious for those whose brains aren't fully developed yet. That includes adolescents, teens and even those in their early twenties.

"We have good reason to believe from both animal and human studies that exposure to marijuana during this important time of brain development can permanently change the way the brain develops," said Thurstone. "We have good evidence showing that marijuana exposure in adolescents confers up to an eight-point drop in IQ from age 13 to 38. We know that youth who use marijuana are two times more likely to develop psychosis as young adults."

The city and county of Denver, arguably the marijuana mecca of Colorado, says it's also heard many concerns from residents.

Ashley Kilroy, Denver's executive director of marijuana policy, says the city is working on a public outreach campaign and in no way promoting the new retail marijuana industry.
"The city is doing its job to fairly and in a balanced way, implement sensible regulations around the marijuana industry," Kiloy said.